Bacillus thuringiensis (Bt), a gram positive bacterium, produces crystalline inclusions composed of proteins during the late stage in sporulation. These proteins are toxic to many insect pests of agricultural importance. Native and several data sets were collected and reduced. Two useful heavy atom derivatives were identified and the heavy atom positions solved and refined. Electron density maps based on the two derivatives were computed. Interpretation and model building is currently in progress. It appears that the heavy atom derivatives are not sufficiently isomorphous to yield a readily interpretable map. The progress of the structure solution depends on additional isomorphous heavy atom derivatives, and hence will need additional synchrotron time for further derivative search and data collection.